Ratchet gear mechanism



D. D. PANABAKER r MM5 RATCHET GEAR MECHANISM `Filed Aug. 2l., 1936 2Sheets-Sheet l y vlvm/Emma amemgpamaer w @W4/f ATTNEY Y Hmm w3.' D. D.PANABAKER '2,1L405 RATCHET GEAR MECHNISM FildAug. 21, 1956 2Sheets-Sheet 2 Mmmm? mm wm? Q m Q Patented June 21, 1938 RATCHET GEAR.MECHANISM David Deane Panabaker, StlMarys, Ontario, Canada ApplicationAugust 21, 1936, serial No.197,277 6 claims. `(C1. 74-124) My inventionrelates to speed reducing gear` mechanisms, and more particularly tospeed reducing gear mechanism employing a ratchet gear which imparts anintermittent rotative movement to a driven shaft.

Heretofore ratchet gear mechanisms have been devised, particularly ofthe type employing ratchet pawls engaging with teeth in the periphery ofa ratchet wheel, but the use of such mechanisms in industry has beenseverely limited, due in part at least to the fact that the ratchetmeans employed has been unduly large and complicated and has lacked theruggedness and long operating life of equivalent means imparting acontinuous rotative movement to the driven shaft. Moreoventheincorporation in such devices of the prior art of means for varying theratio of speed reduction has heretofore further complicated and enlargedthe structure, with a consequent further decrease `in the desirabilityof the unit in industrial employment.

It is an `object of my invention to provide a means for imparting anintermittent rotative motion at `reduced speed to a driven shaft, whichwill be both ncompact and rugged, simple, 5economically manufactured andreadilyA assembled, and which `will have a long useful life atrelatively heavy loads. f

Itis a further object of my `invention to provide `a reducing gear.mechanism employing. a ratchet gear with which is incorporated asimple, readily adjustable means for providing more than one ratio Yofspeed reduction. I

The features of my invention which are be- 35 lieved `to be novel andpatentable are set out with particularity in the claims appended`hereto. For a better understanding of myl invention and of the objectsand advantages thereof,

reference should now be had to the Afollowing '40 particular descriptionand to the drawings attached thereto, in `which 1 Fig. 1 is anelevational drawing `partly in section illustrating one form of myinvention adapted for a constant ratio of speed reduction;

Fig. 211s "a sectional `drawing on the line 2--2 of Fig. l1; and

Figs. 3 and 4 are respectively a plan view, and a sectional View similarto Fig. 2, of another form of my inventionadapted to give a half speedand a zero speed ratio." f Referring now particularly to Figs.1`and 2 vIhave shown the speed reduction ratchet gear mechanism of my inventionmounted in" acasing or box I which maybe and preferably is made in asingle casting and is provided with suitable exterior apertured lugs 2adjacent one wall thereof by means of which the unit may be bolted to avertically extending wall. vIt may be desirable to provide a cover forthercasing, and for this purpose there are provided the lugs 2a adjacentthe top of the casing, each having a tapped hole therein for thereception of suitable securing screws. The output or driven shaft 3 ofthe mechanism of my invention is journalled at one end in a suitablebearing 4 provided in the front wall of casing I, and is journalled atits other end in a sleeve 5 which is preferably integral with theratchet wheel The sleeve 5 in turn is journalled in a suitable bearing'I provided in the rear wall of casing I and a driving overloadprotective connection is made between the sleeve 5 and shaft 3 by meansof the soft steel shear pin B which extends through suitable aperturesin both the sleeve 5 and shaft 3. The forward and rear ends 3a and 9brespectively of the driven shaft 3 are formed into portions ofnon-circular cross section for the purpose of providing a ready meansfor connecting thereto the member to be driven thereby. The end 9a ofshaft 3 is also formed with Va flange II) and suitable washers II areprovided between the flange I0 andthe outer surface of casing I to forma dust protecting seal for the bearing 4.

The ratchet Wheel 6 of suitable relatively large I diameter ispreferably formed integral with the sleeve 5 but may be secured theretoin any man ner so that rotation of` the wheel 6 rotates the sleeve 5thereby driving the shaft 3. Each face of the wheel 6 is provided withan annulus of ratchet teeth I2, the operative tooth faces extendingalong radii of the wheel 6. Ratchet pawls I3 and I4 each in the form ofa plate and each having an annulus of ratchet teeth I5 and Irespectively, are located adjacent the Working faces of the ratchetwheel 6, the ratchet teeth I5` and I6 on the pawls I3 and I4respectively cooperating with the teeth I2 on opposite faces of thewheel 6, Pawl I3 is provided with a bearing I'I journalled over thesleeve 5 and is biased toward the adjacent face of the ratchet Wheel 6by means of the spring I8. Ratchet pawl I4 is similarly provided with abearing I9 journalled over the shaft 3 and is biased toward the otherface of the ratchet Wheel by means of the spring 20. I

A second shaft 2I is mounted in casing I adjacent the periphery ofratchet wheel 6, with its aXis extending parallel to that of the drivenshaft 3. A pair of oppositely disposed eccentrics 22 CII and 23 aremounted for rotation on shaft 2|, each located opposite one of theratchet pawls I3 and I4. Ratchet pawl I4 is provided with a pair oflaterally extending arms 24 and 25 formed integral therewith and spacedapart to form therebetween a slot of sufficient Width to receive theeccentric 23, and the forward arm 25 is provided with a reinforcing rib26. Pawl I3 is also provided with similar arms extending laterallytherefrom and arranged to engage on opposite sides of the eccentric 22,and a reinforcing rib 2l' is also provided on the forward arm 28 of thispawl. It will be understood that the mechanism, in which case a portionthereof would extend outside of the casing for convenient connection toa source of rotative motion such as an electric motor and a suitabledriving connection would be made between shaft 2| and the eccentrics. Inthe modification of my invention illustrated in Figs. l and 2, however,the shaft 2 I is acountershaft on which are mounted the eccentrics 22and 23 arranged to be driven by means of worm gear 29 engaging with aworm 30 on a drive shaft 3| which is mounted in suitable bearings incasing I and extends transversely of shaft 2|. Conveniently theeccentrics 22 and 23 and the worm wheel 29 are made in a single castingand this casting is loosely mounted for rotation on the shaft 2|. Thedrive shaft 3| extends outside of casing I and may be directly orotherwise connected to an electric motor (not shown) or other suitablemeans for providing rotative motion.

In operation the drive shaft` 3| drives the eccentrics on thecountershaft 2| at a suitable reduced speed through the worm 3i) andworm wheel 29. The oppositely disposed eccentrics 22 and 23 in rotationabout the axis of shaft 2| oppositely oscillate the ratchet pawls I3 andI4 alternately backward and forward, each pawl in its forwardoscillation engaging with the teeth I2 on its side of the ratchet wheel6 to thereby drive the shaft 3, and in a backward oscillation riding upthe sloping surface of the teeth I2 against the bias of'springs I8 and20 respectively. The angle A through which each pawl is moved in each ofits complete forward or backward oscillations is 2 tan-l e designatingthe eccentricity of the cams 22 and 23 and d the distance between theaxes of shafts 2| and 3. Assuming that the pawl I3 is just beginning aforward oscillation and is in driving engagement with the teeth on theratchet wheel, during the first half revolution of the eccentric 22 onshaft 2| the ratchet wheel will be turned through an angle A. During thenext half revolution of the eccentrics `on shaft 2|, the ratchet wheelis driven through a further angle A by the pawl I4 and the pawl I3 isVreturned to its rearmost position to again engage the teeth of .i theratchet wheel. Thus during a complete revois oscillated backward whilethe other is oscillated forward, and wherein each pawl engages the teethon the ratchet wheel at the beginning of its forward oscillation, theangle between successive teeth on the same side of the ratchet wheel cannot be greater than 2A; and the number of teeth N on one side of theratchet wheel is given by 360 N-k 2A 1c being any integer. When K=1 orany other odd integer it will be apparent since the pawls are oppositelyoscillated that the teeth on opposite sides of the ratchet wheel must bearranged in staggered relation (as shown in Fig. l) whereas if :2 or anyother even integer the teeth on opposite sides of the ratchet wheel willbe exactly opposite each other (as shown in Fig. 3).

It will be observed, in the case of Fig. 1, wherein lc=l,r that, if forany reason one of the pawls I3 or I4 should fail to be oscillated in thebackward direction through the full angle A, the teeth thereon would notengage with a tooth face on the ratchet wheel 6, and the pawl would besubsequently oscillated idly in the forward direction. In the case ofthe modification of my invention shown in Figs. l and 2 this wouldresult in a complete cessation of rotation of the ratchet wheel 6 anddriven shaft 3. In Figs. 3 and 4 I have illustrated a mechanism similarto that shown in Figs. l and 2 but wherein means have been included toreduce or eliminate the backward throw of one or both pawls and whereink: has been selected as 2 in order to take advantage of the reducedbackward oscillation of the pawls in order to obtain a half speed of thedriven shaft, assuming a constant speed of the drive shaft.

As in Figs. l and 2, the modification of my invention shown in Figs. 3and 4 comprises a driven shaft 3 having a ratchet wheel mounted thereonwith ratchet teeth in each face thereof, a pair of ratchet pawls I3 andI4 in the form of plates mounted for oscillation about the axis ofrotation of shaft 3 and provided with ratchet teeth adapted to engagewith the teeth on the ratchet wheel, each pawl being spring pressedagainst one face of the ratchet wheel, a countershaft 2| on which aremounted for rotation a pair of eccentrics 22 and 23, and a drive shaft3| provided with a worm 30 arranged to drive a worm wheel 29 mounted onthe shaft 2|. Each of the pawls I3 and I4 is provided with armsextending laterally adjacent to its respective eccentric, the forwardarms of the pawls being provided with reinforcing ribs 26 and 2'Irespectively. In the embodiment of my invention shown in Figs. 3 and 4,however, the rear arm of pawl I4 is formed into a circular verticallyextending socket 32 within which is received the end of a cylindricalrod 33. The rod 33 extends vertically beyond the top of casing I and isprovided at its upper end with a lever 34 whereby it may be convenientlyrotated in the socket 32. The rod 33 is also provided, adjacent theeccentric 23, with an offset surface 35 so arranged that when the rod 33is turned to one position the distance between the surface 35 and theoperating face of arm 25 is substantially equal to the diameter of theeccentric 23, and when rod 33 is turned to a position 90 from the firstposition, this distance is substantially greater than the diameter ofthe eccentric 23. Pawl I3 is likewise provided with a similar socket 36receiving the rod 3'I having control lever 38 and offset surface 39 andin Fig. 3 I have shown the rods 33 and 3'I respectively in the twopositions above referred to. Conveniently, means (not shown) may beprovided on the rods 33 and 31 cooperating with the cover of casing I topositively hold the rods in one of their .two positions. The operationof `the mechanism vshown Vin Figs. 3 and 4 when both rods 33 and 31 arein the operative position, i. e. in the position of `rod 33 in Fig. 3,is substantially the same as that of the mechanism `of Figs. 1 and. 2,each Vof the pawls being .alternately oscillated backwards and forwards,each `pawl alternately .driving the ratchet wheel and driven shaftduring its 4for-- ward oscillation.

Due to the selection of the value 2 for lc in the foregoing formula l iY each pawl in its forward oscillation drives the ratchet wheel throughan angle A, which is equivalent to one tooth space on the ratchetwh-eel, and in its backward Voscillation rides idly over one tooth andengages the tooth'second back of that it engaged `for its previousforward oscillation. Thus when both pawls are operative, the shaft 3 isdriven through an angle 2A for each complete revolution of theeccentrics about shaft 2|.

Let it now be assumed that at the beginning of the forward oscillationof one pawl, the control -lever for that pawl Vis moved to `theinoperative position i. e. the position of rod 3T in Fig. 3. During thenext half revolution of shaft 2| the one pawl drives the ratchet wheeland shafty 3 through the angle A while the opposite pawl is beingretracted through an equal angle, passing idly over one toothon theratchet wheel. During the next half revolution'of the shaft 2| theopposite pawl drives the ratchet wheel through an angle A, but, owing tothe inoperativeness of the offset surface on the rod of the first pawl,this pawl is not retracted through the full angle A but through someangle less than A. As a consequence the first pawl does not engage witha tooth face on the ratchet wheel and during the next half revolution ofshaft 2l this pawl moves idly forward over a tooth surface on theratchet wheel. During this half revolution of shaft 2l, the ratchetwheel and shaft 3 lare not turned, and the opposite pawl is 'retraced afull angle A to engage with the next tooth on the adjacent face of theratchet wheel. Thus under these conditions, during a complete revolutionof the shaft 2|, the ratchet wheel is rotated through an angle A onlyand a half speed is obtained.

If both control levers are at the same time in the inoperative position,it is obvious that a zero speed is obtained, both pawls being thus madeinoperative to drive the ratchet wheel. Such an adjustment is sometimesdesirable where the motor used to drive the gear reduction mechanisms isalso used to drive other mechanisms, the operation of which may bedesired independently of that of the gearreduction mechanism. In themechanism shown in Figs. 1 and 2 a zero speed adjustment might beobtained by providing one `of the pawls with a control lever as in Figs.3

and 4. In that case the reduction of the backward throw of one pawlwould make both pawls completely inoperative to drive the ratchet wheel.

Although in the foregoing description I have selected the,values 1(Figs. l and 2) and 2 (Figs. 3 and l) for 7c in the formula 350 N k 2Aand have pointed out how a half and a zero speed of the driven shaft maybe obtained, it will be apparent that other fractional speeds of thedriven shaft may be-obtained by suitably selecting a value for 1c andvarying the backward throw of one or both pawls. I do not wish to belimited to the specific modifications shown, and in the appended claimsI aim to cover all such variations or modifications of my invention asfall within the time spirit or scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. A ratchet gear reduction mechanism comprising a shaft, a ratchetwheel mounted on said shaft and having teeth in the face thereof, a pawlmounted for oscillation about the axis of said 'shaft adjacent the faceof said ratchet wheel means for biasing said pawl into engagement withthe teeth on said face, a second shaft having its axis extendingsubstantially parallel to that of said first shaft, an eccentric mountedon said second shaft for rotation about the axis thereof, means forrotating said eccentric, means extending from said pawl and having asurface adjacent one side of said eccentric whereby said pawl isoscillated in a forward direction as said eccentric is rotated, andmeans extending from said pawl and having a surface adjacent the otherside of said eccentric whereby said pawl is oscillated in a backwarddirection as said eccentric is rotated, said last-named means includinga rod mounted in a socket formed in said pawl and having an offsetsurface adapted `to co-operate with said eccentric, said rod beingrotatable in said socket about its longitudinal axis to vary theco-operative engagement of said offset surface and said eccentric,whereby the angle through which said pawl is oscillated'to drive saidratchet ywheel may be varied.

2. A ratchet gear reduction mechanism-comprising a shaft, a ratchetwheel mounted on said shaft and having teeth in the face thereof, a pawlmounted for oscillation about the axis of said shaft adjacent the faceof said ratchet wheel means for biasing said pawl into engagement withthe teeth in said face, a second shaft having its axis extendingsubstantially parallel to that of said first shaft, an eccentric mountedon said second shaft for rotation about theraxis thereof, means forrotating said eccentric, means extending from said pawl and having asurface adjacent one side of said eccentric whereby said pawl isoscillated in a forward direction as said eccentric is rotated, meansextending from said pawl and having a surface adjacent the other side ofsaid eccentric whereby said pawl is oscillated in a backward directionas said eccentric is rotated, said last-named means including a rodmounted in a socket formed in said pawl and having an offset surfaceadapted to co-operate with said eccentric, said rod being rotatable insaid socket about its longitudinal axis to move said offset surface intoand out of co-operative engagement with said eccentric whereby said lastnamed means extending from said pawl may be made ineffective tooscillate said pawl through a complete backward oscillation.

3. A ratchet gear reduction mechanism comprising a shaft, a ratchetwheel mounted on said shaft and having teeth in each face thereof, apawl mounted adjacent each face of said ratchet wheel for oscillationabout the axis of said shaft, and having ratchet teeth adapted to engagewith the teeth in the adjacent face of said wheel, a second shaft, aneccentric mounted on said second shaft opposite each of said pawls,means to rotate said eccentrics about the axis of said second shaft, apair of arms extending `from each of said pawls and having surfacesadjacent opposite sides of said eccentrics whereby when said eccentricsare rotated said pawls areV oscillated through a given angle, one ofsaid arms including a rod mounted at one end in a socket formed in thepawl and having'an offset surface arranged to co-operate with therespective eccentric, said rod being rotatable about its longitudinalaxis in said socket to vary the cooperative relation between saidyoffset surface and said eccentric whereby when said eccentrics arerotated one of said pawls may be arranged to oscillate through an angleless than said given angle.

4. In a ratchet gear reduction mechanism comprising a ratchet wheelhaving teeth in a face thereof, a pawl mounted adjacent to the face ofsaid ratchet wheel for oscillation about the axis of rotation of saidwheel, a shaft, an eccentric mounted for rotation about the axis of saidshaft, means for rotating said eccentric and a pair of arms extendingfrom saidpawl and having surfaces adjacent opposite sides of saideccentric whereby when said eccentric is rotated said pawl is oscillatedthrough a given angle, one of said arms including a rod mounted at oneend in a socket formed .in said pawl and having an offset surfacearranged to co-operate with said eccentric, said rod being rotatableabout its longitudinal axis in said socket to vary the co-operativerelation between said offset surface and said eccentric.

5. A ratchet gearreduction mechanism comprising a casing, a shaftmounted at one end for rotation in a wall of said casing, a sleevemounted for rotation in the opposite wall of said casing, the other endof said shaft being journalled with.

in said sleeve, means located outside of said casing and securing saidshaft and sleeve together and forming a driving overload protectiveconnection therebetween, a ratchet wheel secured to one end of saidsleeve and mounted within said casing about said shaft and havingratchet teeth in each face thereof, a ratchet pawl plate mounted foroscillation about the axis of said shaft adjacent each face of saidratchet wheel and having teeth adapted to co-operate with the teeth inthe adjacent face of the wheel, means for biasing each of said pawlplates into engagement with the ratchet wheel, a second shaft mounted insaidcasing with its axis substantially parallel to that of said firstshaft, an eccentric mounted on said second shaft opposite each of saidpawl plates, means for rotating said eccentrics about the axis of saidsecond shaft, and a pair of arms extending from each of said pawl platesand engaging on opposite sides of the respective eccentric whereby assaid eccentrics are rotated said pawl plates are oscillated to drivesaid ratchet wheel and first shaft.

6. A ratchet gear reduction mechanism comprising a casing, a shaftmounted at one end for rotation in one wall of said casing, a sleevemounted for rotation in the opposite wall of said casing, the other endof said shaft being journalled within said sleeve, a shear pin securingsaid shaft and said sleeve together and extending therethrough outsideof said casing, a ratchet wheel formed integral with said sleeve andmounted within said casing about said shaft and having ratchet teeth ineach face thereof, a ratchet pawl plate mounted on said sleeve adjacentone face of said ratchet wheel and having teeth adapted to cooperatewith the teeth in the adjacent face of said wheel, another ratchet pawlplate mounted on said shaft adjacent the other face of said wheel andhaving teeth adapted to cooperate with the teeth in the adjacent face ofsaid wheel, means for biasing each of said pawl plates into engagementwith said ratchet wheel, a second shaft mounted in said casing with itsaxis extending substantially parallel to that of said rst shaft, aneccentric mounted on said second shaft opposite one of said pawl plates,an oppositely disposed eccentric mounted on said second shaft oppositethe other of said pawl plates, means for rotating said eccentrics inunison about the axis of said second shaft, and a pair of arms extendingfrom each of said pawl plates and engaging on opposite sides of therespective eccentric whereby as said eccentrics are rotated said pawlplates are oppositely oscillated to alternately drive said ratchet wheeland first shaft.

D. DEANE' PANABAKER.

